For different types of treatment, putting a tubular prosthesis in place inside a blood vessel, whether a vein or an artery, is known. Such tubular prostheses are generally designated by the term “stent”. WO-A-2005/079705 describes such a prosthesis. The prosthesis is introduced inside the vessel while the prosthesis is in the retracted state. Then, to put it in place, the prosthesis is expanded so as to be applied against the inner surface of the vessel. This expansion occurs either automatically because of the resilience of the prosthesis lattice, or by inflating a small inner balloon, causing plastic deformation of the material making up the lattice.
To avoid subsequent displacement of the prosthesis, the end of the metal lattice has pairs of hooks each forming an engagement clamp to immobilize the prosthesis axially in the vessel.
Each clamp is thus delimited by two hooks carried by the lattice that can move between a spaced-apart position in which the clamp is open and a closer-together position in which the clamp is closed. Each hook is threadlike and has one end fixed to the lattice. The other end of the hook is free and forms an endpiece for engaging in the tissue delimiting the blood vessel.
The two fixing ends of each clamp are carried by the same mesh of the lattice. The hooks are moved from their spaced-apart position to their closer-together position by moving the fixing end thereof when the mesh carrying the clamp expands. The mesh is first held in a retracted state during expansion of the entire lattice, then released to close the clamp.
However, the lattice does not deform uniformly, in particular depending on the morphology of the blood vessel in which it is implanted. The free ends of the hooks forming the same clamp can therefore be separated from each other in particular after expansion of the lattice. This impairs the robustness of the fixture of the lattice in the tissue delimiting the vessel.